Vehicle systems may include various vacuum consumption devices that are actuated using vacuum. These may include, for example, a brake booster and a purge canister. Vacuum used by these devices may be provided by a dedicated vacuum pump. In other embodiments, one or more aspirators (alternatively referred to as ejectors, venturi pumps, jet pumps, and eductors) may be coupled in the engine system that may harness engine airflow and use it to generate vacuum.
In yet another example embodiment shown by Bergbauer et al. in U.S. Pat. No. 8,261,716, a control bore is located in the wall of the intake such that when the throttle plate is at idle position, vacuum generated at the periphery of the throttle is supplied to a vacuum consumption device. Therein, the positioning of the throttle plate in an idle position provides a constriction at the throttle plate's periphery. The increasing flow of intake air through the constriction results in a venturi effect that generates a partial vacuum. The control bore is sited so as to utilize the partial vacuum for a vacuum consumption device.
The inventors herein have identified potential issues with the above approach. As an example, the vacuum generation potential of the throttle is limited. For example, a single control bore at one location in the intake, as shown in U.S. Pat. No. 8,261,716, is utilized by the vacuum consumption device even though vacuum may be generated at the entire periphery of the throttle. To use vacuum generated at the entire periphery of the throttle, more control bores may be needed in the intake passage. However, fabricating these control bores may result in significant modifications to the design of the intake passage, which can increase related expenses.
In the approaches that use one or more aspirators to generate vacuum, additional expenses may be incurred because of individual parts that form the aspirator including nozzles, mixing and diffusion sections, and check valves. Further, at idle or low load conditions, it may be difficult to control the total airflow rate into the intake manifold since the flow rate is a combination of leakage flow from the throttle and airflow from the aspirator. Typically, an aspirator shut off valve (ASOV) may be included along with the aspirator to control airflow but with added cost. Further, installing aspirators in the intake can lead to constraints on space availability as well as packaging issues.
In one example, the issues described above may be addressed by a method for pivoting a spherical throttle to align one of a plurality of passages arranged interior to the throttle with an intake passage of an engine. In this way, a desired amount of vacuum may be supplied to a vacuum consumption device based on the one of the plurality of passages selected, wherein the selection may be based on an engine load and/or vacuum stored in a reservoir of the vacuum consumption device.
As one example, the throttle comprises at least a first passage, a second passage, and a third passage, each configured to align with one or more portions of the intake passage. A diameter of the throttle may be greater than a diameter of the intake passage, thereby separating the intake passage into upstream and downstream passages relative to the throttle via a gap. The upstream and downstream passages may be fluidly separated from one another when one or more of the passages interior to the throttle is misaligned with the upstream and downstream passages. Thus, one or more of the passages located interior to the throttle may bridge the upstream and downstream passages and fill the gap located therebetween. The first, second, and third passages may be differently shaped than one another, thereby allowing the passages to provide disparate intake airflow rates to the engine and vacuum flow rates to a vacuum consumption device. One of the first, second, and third passages may be aligned with the upstream and downstream passages of the intake passage based on a pivoting of the throttle about an axis of a shaft coupled to the throttle. In this way, actuation of the passages is limited, thereby increasing a durability of the vacuum generating throttle compared to other throttle designs, such as the designs described above having sliding components, which may experience a greater amount of friction. Additionally, the throttle is compact and easy-to-install via welds or other similar techniques known in the art.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.